Wetland biofilter chamber with peripheral catch basin and method of use thereof

ABSTRACT

A horizontal flow water treatment method and wetland biofilter apparatus provides a chamber with impermeable outer walls spaced away from permeable interior walls of a media filtration bed such that a catch basin is formed between the outer walls and the interior walls. The catch basin creates an open area around the perimeter of the interior walls for influent water to fill within the open area on all sides before penetrating the filtration media, providing a large surface area for influent water to interact with the media filtration bed. The influent water enters the catch basin in a horizontal flow path to provide for pre-settling of particulates before making contact with the filtration media. The biofilter design increases the available surface area of the media filtration bed by up to four times for a given volume of water, and thereby minimizes the loading or infiltration rate on the media filtration bed.

FIELD OF THE INVENTION

The present invention relates, in general, to a water capture/drainageand treatment system and a method of using the same. More particularly,the present invention relates to a chamber for a wetland biofiltersystem which allows for horizontal flow of water through the system andwhich provides a peripheral catch basin between an outer wall and aninterior wall of the chamber for receiving influent water before itinteracts with a media filtration bed disposed within the interiorwalls.

BACKGROUND OF THE INVENTION

Water treatment systems have been in existence for many years. Thesesystems treat stormwater surface runoff or other polluted water.Stormwater surface runoff is of concern for two main reasons: onebecause of the effects of its volume and flow rate, and two, because ofthe pollution and contamination it can carry. The volume and flow rateof stormwater is important because high volumes and high flow rates cancause erosion and flooding. Pollution and contamination are importantbecause stormwater is carried into our rivers and streams, from thereinto our lakes and wetlands, and furthermore because it can eventuallyreach our oceans. Pollution and contamination that is carried bystormwater can have adverse affects on the health and ecological balanceof the environment.

The Clean Water Act of 1972 set the stage for vast improvements to awater infrastructure and quality. Water pollution has been divided intotwo categories: point source and non-point source. Point sources includewastewater and industrial waste. Point sources are more easilyidentifiable, and therefore direct measures can be taken to controlthem. The other category, non-point source, is more difficult toidentify. Stormwater runoff is the major contributor to non-point sourcepollution in rivers, lakes, steams and oceans. Studies have suggestedand confirmed the leading cause of pollution to our waterways is fromcontaminated stormwater runoff. As we build houses, buildings, parkinglots, roads and other impervious areas, we increase the amount of waterthat runs off the land and into our stormwater drainage systems, whichall lead to rivers, lakes, streams and the ocean. As more land becomesimpervious, less of the rain seeps back into the ground. This leads toless groundwater recharge and higher velocity flows in streams, whichcause erosion and increased loads of contaminants into these waterways.

There are numerous sources of pollutants that are present in stormwaterrunoff. Sediments come from hillsides and other natural areas that aredisturbed during construction and other human activities. When land isstripped of vegetation the soil more easily erodes and finds its way tostorm drains. Trash and other unnatural debris are dropped on the groundevery day which find its ways into the drainage system and ultimatelyour waterways. Leaves from tress and grass clippings from landscapeactivities that land on hardscape areas no longer decompose back intothe ground but flow to our storm drains and collect in hugeconcentrations in lakes and streams. These organic substances leach outhuge loads of nutrients and they decompose and cause large algae bloomswhich deplete the dissolved oxygen levels and kill fish and otherorganisms. Other unnatural sources of nutrients including nitrogen,phosphorus, and ammonia come from residential and agriculturalfertilizers that are used in access and find there way to storm drains.Nutrients are one of the number one pollutants of concern in ournations.

Other major pollutants of concern include heavy metals which come fromnumerous sources and are harmful to fish and other organisms includinghumans. Many of our waterways are no longer safe to swim in or fish inand therefore no longer have any beneficial use. Heavy metals includebut are not limited to zinc, copper, lead, mercury, cadmium andselenium. These metals come from car tires and break pads, paints,galvanized roofs and fences, industrial activities, mining, recyclingcenters, any metal materials left uncovered. Other major pollutants ofconcern are hydrocarbons which include oils & grease. These pollutantscome from leaky cars and other heavy equipment and include hydraulicfluid, break fluid, diesel, gasoline, motor oils, cooking oils and otherindustrial activities.

Bacteria, pesticides and organic compounds are a few other categories ofpollutants which are also harmful to our waterways, wildlife and humans.Over the last 20 years the EPA has been monitoring the pollutantconcentrations in most of the streams, rivers and lakes throughout thecountry. Over 50% of our waterways are impaired for one of more of theabove mentioned pollutants. As part of the Phase 1 and Phase 2 NPDESpermits which control industrial and non-industrial developmentactivities the control of these sources of pollutants in now mandated.Phase 1 was initiated in 1997 and Phase 2 was initiated in 2003. Whilethere are many requirements to these permits the three main focuses areon source control, during construction pollution control and postconstruction pollution control. Post construction control mandates thatany new land development or redevelopment activities are required toincorporate methods and solutions that both control increased flows ofrain water off the site and decrease (filter out) the concentration ofpollutants off of these developed sites. These are commonly known asquantity and quality control. Another part of the these requirements isfor existing publicly owned developed areas to retrofit the existingdrainage infrastructure with quality and quantity control methods andtechnologies to decrease the existing amount of rain water runoff andpollutant concentrations.

One of the main categories of technology that help with obtaining thesegoals are referred to as structural best management practices or BMPs.Structural BMPs are proprietary and non-proprietary technologies thatare developed to store and/or remove pollutants from stormwater. Methodssuch as detention ponds, regional wetlands are used to control thevolume of runoff while providing some pollutant reduction capabilities.Over the past 10 years numerous technologies have been invented toeffectively store water underground and thus freeing up buildable landabove them. Various treatment technologies such as catch basin filters,hydrodynamic separators, media filters are used to remove pollutants.These technologies commonly work by using the following unit processes:screening, separation, physical filtration and chemical filtration.

Other technologies such as bio swales, infiltration trenches, andbioretention areas commonly known as low impact development (LID) orgreen technologies have recently been implemented in the last 10 year toboth control flow volumes and remove pollutants on a micro level. TheseLID technologies have proven successful at removing difficult pollutantssuch as bacteria, dissolved nutrients and metals as they provide notonly physical and chemical, but also biological filtration processes byincorporating a living vegetation element which creates a livingmicrobial community within the media by the plants root systems whichassist in pollutant removal. Biological filtration processes have provento be excellent at removing many of the pollutants that physical andchemical filtration systems alone cannot. While these technologies areeffective they take up substantial amounts of space which are not alwaysavailable on various construction projects. As such a need has arisenfor compact LID technologies that offer the same advantages as theirlarger and space expensive counterparts.

Recent technology advancements in the field have focused on taking thetraditional bioretention concept which is focused around verticaldownward flow media filtration beds that pond water on top of the bedand making them up to 10^(th) of the size smaller by using high flowrate filtration media. As with traditional large bioretention systemsthese new compact bioretention systems accept stormwater runoff directlywithout pre-treatment and therefore receive large amounts ofparticulates that can clog the media filtration bed. This clogging asbeen exacerbated with these compact systems as the surface area of themedia is only one tenth that of the traditional large bioretentionsystems. These downward flow systems are notorious for clogging assediments accumulate on top of the media filtration beds surface. Theneed for a better way of making biofiltration system which allows thesystems to still be compact but maximizes the media surface area for agiven media bed volume. The greater the surface area for a given volumeof bed media the lower the loading rate on the media and therefore lessprobability of clogging. Also, the traditional downward vertical flowpath through a media bed is the most problematic for clogging as gravityallows inflow particulates to quickly and easily accumulate on top ofthe media bed.

Stormwater is characterized by large concentrations of variouspollutants including trash, debris and sediments. Reports have shownthat for urbanized area an average of 7.6 cubic feet of trash and 2.4cubic yards of sediment are generated per acre of impervious surface peryear. In many areas, where proper erosion control measures are nottaken, which is common, the loading of sediment is much higher.Therefore, a system which has a media bed designed to minimize cloggingalong with a pre-treatment chamber to remove trash and sedimentsprovides huge advantages to the end user. The maintenance of allstormwater BMPs can be very expensive and a burden to property owners.There is, thus a need to a system that can minimize maintenance costs.

Also, with changing stormwater regulations, a move is being made fromflow based design to volume based design. Volume based design requirestreatment along with volume control. Volume based design requires notonly a treatment system but a storage system. Only horizontal flow mediabed filters that included live vegetation can be placed downstream ofthe storage system. By having the vegetated media bed filter down streamallows it to also provide the flow control. This eliminates the need fora separate flow control structure which is costly. Having the media bedfilter downstream also allows the water to be metered through the systemover an extending period of time as a much slower flow rate whencompared to flow based design. This further reduces the surface arealoading rate which further minimizes clogging and also drasticallyincreases the hydraulic retention time. The longer the retention timethe higher the performance ability of the system.

Some systems include a wetlands chamber having a vegetative submergedbed, one or more walls, a floor, one or more inlet water transfer pipesand one or more outlet water transfer pipes. Examples of related systemsare described in U.S. Pat. No. 7,425,262 B1, U.S. Pat. No. 7,470,362 B2and U.S. Pat. No. 7,674,378, the contents of each of which areincorporated herein by reference in their entirety. In other systems,each of the walls and floor have an inner and outer metal mesh wall,with a space between the inner and outer walls to house stonewoolfiltration media slabs. Having a catch basin or chamber also includesone or more inflow pipes in one or more of the four walls to allowinfluent to pass into the catch basin. The system is configured so thatthe sediments and associated pollutants settle out of the influent andaccumulate on the floor of the catch basin or chamber. A filtrationpanel comprising four or more walls enclosing an open space housing afiltration media, the walls being water permeable in structure to allowpassage of water in either direction, the filtration media filling theentire inner chamber of the filtration panel and being water permeable.

Contaminated water such as stormwater and waste water contain highlevels of particulate pollutants such as TSS, metals, organics,nutrients and hydrocarbons. These particulates cause media filtrationbeds to clog, which decreases their treatment flow capacity andincreases the maintenance and replacement requirements of the granularmedia within the media filtration bed. Because of this a need has arisenthat further increases the amount of initial media bed surface area fora given volume of filter media. By increasing the amount of availablemedia bed surface area for a given volume of media the surface loadingrate decreases for a given flow of water and therefore decreases therate at which media will clog due to particulates.

Traditional downward flow media filtration beds have their initial mediasurface area lay horizontal perpendicular with the force of gravity.Therefore, pollutant particles accumulate on top of the media bed andclog the media at a much faster rate and thereby decreasing the mediafiltration bed's flow rate and performance, along with increasing therequired maintenance and decreasing the life of the media beforereplacement is needed.

With the ever changing stormwater regulations a system that providesfeatures that lowers maintenance costs, increases performance andpollutant removal and can be integrated with storages systems and placeddownstream are in great need and demand. The smaller these systems arethe easier they can be integrated into urban areas with limited room.The easier it is made to incorporate these systems in urban areas thegreater overall affect we will have at reducing pollution to ourprecious rivers, lakes and streams.

SUMMARY OF THE INVENTION

Embodiments described herein are directed to a horizontal flow wetlandbiofilter system comprising including a chamber with impermeable outerwalls spaced away from permeable interior walls of a media filtrationbed to form a peripheral catch basin. The catch basin provides an openarea around the perimeter of the interior walls for influent water tofill within the open area on all sides of the chamber, thereby providinga large surface area for influent water to penetrate the filtrationmedia. The influent water enters the chamber and penetrates the mediafiltration bed in a horizontal flow path in order to provide forpre-settling of particulates before making contact with the mediafiltration bed. The chamber may be disposed below ground and connectedwith an adjacent chamber for receiving influent water. The chamber mayadditionally include a flow control orifice or flotation valve tofurther regulate the flow of water through the chamber.

In one embodiment of the invention, a wetland biofilter chambercomprises: one or more outer side walls and a floor section defining asubstantially enclosed chamber; a media filtration bed disposed withinthe chamber and defined by one or more permeable inner side walls,wherein the permeable inner side walls of the media filtration bed areseparated from the outer side walls of the chamber and define a catchbasin for receiving an influent; a collection tube disposed within themedia filtration bed and extending vertically from a top portion of themedia filtration bed to a lower portion of the media filtration bed; andat least one outlet opening connecting the lower portion of thecollection tube with an outside of the chamber.

The outer side walls and floor section may be impermeable.

The one or more outer side walls may include an intake opening toreceive an influent into the catch basin.

The intake opening may be located on a lower half of a side wall.

The wetland biofilter chamber may further comprise an outlet tubedisposed horizontally across the floor section of the chamber andconnecting the collection tube with the at least one outlet opening.

The collection tube may be permeable.

The permeable collection tube may be perforated.

The height of the collection tube may be approximately 5% toapproximately 100% of the height of the media filtration bed.

The collection tube may further comprise a restriction plate whichrestricts the flow of filtered influent to the outlet tube.

The restriction plate may be connected with a flotation valve disposedwithin the collection tube which controls the restriction plate based ona level of influent in the collection tube.

The catch basin may have a width of approximately 0.1 inches toapproximately 10 feet.

The catch basin may have a width of approximately 1 inch toapproximately 2 feet.

The height of the inner side walls may be approximately 25% toapproximately 100% of the height of the chamber walls.

The thickness of the media filtration bed may be approximately 0.25inches to approximately 80 feet.

The thickness of the media filtration bed may be approximately 1 toapproximately 4 feet.

The catch basin may include a substantially hollow structural matrix.

In another embodiment, a method of filtering influent in a biofilterchamber comprises: receiving an influent into a catch basin of thebiofilter chamber, wherein the catch basin is disposed around an innerperiphery of the chamber between one or more outer side walls of thechamber and one or more inner permeable inner side walls of a mediafiltration bed; filtering the influent through the media filtration bed;collecting the filtered influent from the media filtration bed at acollection tube extending vertically within the media filtration bedfrom a top portion of the media filtration bed to a lower portion of themedia filtration bed; passing the filtered influent from the collectiontube to at least one outlet opening connected with an outside of thebiofilter chamber.

The method may further comprise receiving the influent into the catchbasin from an intake opening located on a lower half of a side wall.

The method may further comprise receiving the influent into the catchbasin from an intake opening located on an upper half of a side wall.

The method may further comprise receiving the influent into the catchbasin from an opening in the top of the biofilter chamber.

The method may further comprise passing the filtered influent from thecollection tube to the at least one outlet opening using an outlet tubedisposed horizontally across the floor section of the chamber andconnected on a first end with the collection tube and on a second endwith the at least one outlet opening.

The method may further comprise restricting the flow of influent using arestriction plate disposed within the collection tube.

The method may further comprise restricting the flow of filteredinfluent when a flotation valve disposed within the collection tube andconnected with the restriction plate falls below a defined level.

The method may further comprise receiving the influent from an adjacentstorage chamber or pre-treatment chamber.

From this description, in conjunction with other items, the advantagesof the said invention will become clear and apparent more so based uponthe hereinafter descriptions and claims, which are supported by drawingswith numbers relating to parts, wherein are described in the followingsections containing the relating numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention and,together with the description, serve to explain the objects, advantages,and principles of the invention. In the drawings:

FIG. 1 is a top plan view of an embodiment of a horizontal flow wetlandbiofilter system with a catch basin;

FIG. 2 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system;

FIG. 3 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system installed below a groundsurface level which receives water from an adjacent impervious surfacearea;

FIG. 4 is a top plan view of an embodiment of the horizontal flowwetland biofilter system where the catch basin is formed of a hollowstructural matrix;

FIG. 5 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system showing the hollow structuralmatrix forming the catch basin;

FIGS. 6A and 6B are front and side views, respectively, of an embodimentof the hollow structural matrix illustrating openings on all sides ofthe hollow strucrutal matrix;

FIG. 7 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system installed below the groundsurface level and connected with an adjacent underground water storagesystem;

FIG. 8 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system installed below the groundsurface level and connected with an adjacent above-ground water storagesystem;

FIG. 9 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system installed below the groundsurface level and separated by a common wall from an adjoining chamberwhich contains a settling area;

FIG. 10 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system where the adjoining chambercontains screens to remove trash and debris from inflowing water;

FIG. 11 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system where the adjoining chambercontains a plurality of media filter cartridges;

FIG. 12 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system where the adjoining chambercontains a media filtration bed with a lower drain and a solid top;

FIG. 13 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system where the adjoining chambercontains a media filtration bed with a lower drain and an open top;

FIG. 14 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system where the system is connectedwith an adjacent horizontal flow wetland biofilter system;

FIG. 15 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system illustrating hydraulic gradelines in the chamber upstream and downstream of an orifice flow controlplate;

FIG. 16 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system with a perforated tubecontaining a float valve in a closed position;

FIG. 17 is a side elevational section view of an embodiment of thehorizontal flow wetland biofilter system illustrating the float valve inan open position;

FIGS. 18A and 18B are side and front views, respectively, of a floatvalve with a small flow orifice extending along a base of a valve stop;and

FIG. 19 is a top plan view of an embodiment of the horizontal flowwetland biofilter system illustrating a permeable inner wall with anirregular surface area.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

After reading this description it will become apparent to one skilled inthe art how to implement the invention in various alternativeembodiments and alternative applications. However, all the variousembodiments of the present invention will not be described herein. It isunderstood that the embodiments presented here are presented by way ofan example only, and not limitation. As such, this detailed descriptionof various alternative embodiments should not be construed to limit thescope or breadth of the present invention as set forth below.

Overview

A water filtration apparatus with a unique filtration chamber designthat maximizes the available surface area of filtration media for agiven volume of water will be described herein. The water filtrationsystem includes an enclosed chamber that houses a media filtration bedand a structural matrix or permeable wall that creates a void space, orcatch basin, between the chamber's outer side wall(s) and the innersurface walls of the media filtration bed. The catch basin creates acontinuous open area around the perimeter of the media filtration bedbetween the media filtration bed perimeter and the chamber side walls,so that influent contaminated water will fill the catch basin beforepenetrating the media filtration bed. With the media filtration bedencompassed within internal permeable walls spaced from the chamber sidewalls, the apparatus provides up to four times more surface area than adownward flow bioretention system.

The water filtration apparatus also operates by horizontal flow, suchthat the influent water is received at a side portion of the apparatus,such as through an opening in one of the chamber side walls or even anopening in the bottom surface of the chamber. The horizontal flow pathallows for contaminated water to enter the chamber sub-surface via pipeor sheet flow into the top of the chamber. The benefits of horizontalflow will be described further herein.

Exemplary Embodiments

With reference to FIGS. 1 and 2, an embodiment of a horizontal flowwetland biofilter system chamber 100 are shown and will be described,the chamber 100 being composed of a floor 120 defined by walls 110running generally perpendicular to the floor 120 on all sides. One ofthe walls with an opening 205 in which a pipe 200 allows water to flowinto the chamber subsurface and into the perimeter catch basin 230 whichis defined as the area between the chamber walls 110 and the internalpermeable walls/partitions 250. The perimeter catch basin 230 extendsvertically from the floor 120 upward to the top of the chamber walls110. Water may fill the chamber to the top of the chamber walls 110 orto a height equal to the invert of an upstream bypass outside of thechamber 100. As the water fills up the column of the catch basin largerparticulates present in the water will settle to the floor. Also, aswater fills the perimeter catch basin on all sides 230 it builds uphydraulic head pressure which provides the forced needed for it to flowhorizontally inward through the permeable walls/partitions 250 which aremade of a material that has a generally high open area for maximum waterflow with the opening beings smaller in size than the media granules ofthe media filtration bed 400 held within the interior of the permeablewalls/partitions 250. In one embodiment, the catch basin may have awidth of approximately 1 inch to 24 inches, but generally it is at leastapproximately 6 inches wide in order to facilitate access by a standardvacuum hose for cleaning.

The permeable walls/partitions mirror the chamber walls in shape putwith a smaller perimeter length. The permeable walls/partitions containthe media filtration bed. In general, the permeable walls/partitions areat least 25% the height of the chamber walls and may be the same heightas the chamber walls. The permeable walls/partitions are created byseveral yet similar methods are not limited to the following: perforatedmetal, pervious pavers, concrete, or asphalt, geofabric, netting,screens and structural matrixes that are covered in a netting or screen.The permeable walls/partitions have openings that are generally smallerthan the size of the granules within the media filtration bed. Ingeneral, the permeable walls/partitions have at least 30% void space.The permeable walls/partitions must of sufficient strength not to warpin shape and must maintain the void space between the media filtrationbed and chamber walls on all sides to insure a continuous perimeter voidarea to allow water to flow around with impediment.

The media filtration bed extends the height of the permeablewalls/partition or structural matrix. The said media filtration bed iscomposed of various granular filtration media in various sizes andquantities. The composition of the media mix can vary depending on thetargeted pollutants of concern. Types of media used are the followingbut not limited to: perlite, expanded aggregate, soil, compost, wastewater residuals, zeolite, polymers, stone, top soil, sand, activatedcharcoal, iron oxide, aluminum oxide, bio balls, stonewool or rockwool,and other organic or inorganic materials. The flow through the media ishorizontal from its surface adjacent to the permeable walls/partitionsto the perforated tube in the middle. The thickness of the media can bebetween a few centimeters to hundreds of feet. In general, the thicknessof the media is between 12 and 48 inches. The top of the mediafiltration bed contains blocks or a mat of inorganic material such asrockwool, stonewool, coconut coir or similar that are placed just belowthe surface of the media filtration bed and laid in a horizontalorientation. The purpose of the said material is to provide a base forthe establishment of plants and vegetation. The referenced material isgenerally used for the growing of plants by the hydroponic method whichis also referred to as soil-less agriculture. The materials referencedabove retain the moisture in the perfect air to water ratio for plantlife.

As water flows horizontally through the media filtration bed 400,pollutants carried in the water such as hydrocarbons, particulates,metals, nutrients, pathogenic bacteria and chemicals are removed by acombination of physical filtration, chemical filtration and biologicalfiltration. The inclusion of vegetation 500 growing out the top of thechamber 100 within the media filtration bed 400 allows for theestablishment of their root systems 520 to take place. The root systemspenetrate vertically downward through the column of the media filtrationbed 400 which enhances the biological removal of pollutants throughsorption, transformation and uptake by the root system 520 and thesurrounding beneficial microbial community. The establishment ofvegetation in biofilter system is generally difficult because thegranule media in the media filtration bed 400 is fast draining and doesnot hold enough moisture close to the surface for the vegetation rootsystems to establish. To overcome this, a layer of soil-less inertgrowing media 800 is laid just below the surface of the media filtrationbed 400 horizontally where the vegetation's root system will start toestablish. The soil-less grow media 800 is generally made of rockwool,stonewool, coconut coir or similar which is designed to have a highinternal void space and hold substantial amounts of moisture whileproviding an ideal air water ratio to optimal plant growth.

Collection Tube

The water travels, horizontally, through the media filtration bed 400toward the center of the chamber which contains a vertically extendingtube 420 which has a series of horizontally perforated slots 425 thatare spaced vertically from the bottom to the top of the tube. Theperforations 425 allow water to enter the inside of the tube 420 andtravels downward, at the bottom of the chamber 100 the perforated tube420 is connected to by a 90 degree elbow to a solid horizontal tube 300that connects to an opening in the chamber wall 305 which allows waterto exit the chamber. In some embodiments the horizontal tube 300contains an internal orifice plate 440 which has a smaller diameter thanthe interior diameter of the tube 300. The orifice plate control themaximum amount of flow that is allowed to be processed through thehorizontal flow wetland biofilter system chamber 100. The verticallyextended perforated tube 420 has a cap 430 on the top that protrudes outof the top of the chamber 100 and allows for clean out.

The tube extends at least 5% the height of the permeablewalls/partitions and generally extends to the same height as the saidpermeable walls/partitions. The top of the perforated tube is fittedwith a cap that can be removed for cleaning out or other maintenanceactivities if needed. The perforated tube has a series of slots machinedin it that run horizontally. The widths of the slots are equal to orsmaller in size than the granular media which compose the mediafiltration bed. In some embodiments the perforated tube is wrapped in anetting sleeve when the granular media is smaller than the tubeperforations. The perforations run from the bottom of the bottom of thetube where it comes in contact with the floor and they extend upvertically at least 50% the height of the tube. The vertically extendingperorated tube connects, adjacent to the floor, to a non-perforatedhorizontally laying tube. This tube connects to the opening in the sidewall of the chamber. In other embodiments the vertically extendingperforated but connects directly to an opening in the floor in order toallow treated water to exit the chamber.

The horizontal flow wetland biofilter system, in some embodiments isplaced at ground level with the top of the chamber 100 (FIG. 3) equal tothe elevation of ground level 220. Stormwater runoff from the surfacesadjacent to the horizontal flow biofilter system is allowed to flowtoward and directly into the perimeter catch basin 230 of the chamber.On sides of the chamber 100 in which flow is not needed to enter aconcrete or asphalt curb 260 is built with a top elevation higher thanthe top of the chamber wall 110. In this embodiment, stormwater or othercontaminated waters are allowed to enter the system directly by means ofsheet or surface flow.

Hollow Structural Matrix

In some embodimenst of the horizontal flow wetland biofilter system thechambers 100 (FIG. 4) perimeter catch basin 230 is created by theinclusion of a hollow structural matrix 270 which is another embodimentof the same invention. The hollow structural matrix 270 has a largesurface and internal voids which makes up a majority of its volume. Thevoid hallow areas have open paths 275 (FIG. 6) which allows water toflow in any direction unimpeded. The surface of the structural matrix ishighly void with large openings. To prevent granules from the mediafiltration bed from entering the internal voids of the hollow structuralmatrix 270 it is covered or wrapped in netting, screen, fiber or similar280. The hollow structural matrix 270 is covered in the netting 280 onat least the side that is adjacent to the media filtration bed 400 andgenerally covered on all sides. The hollow structural matrix 270 isstrong enough to support the weight of the lateral loading of the mediafiltration bed 400. In one embodiment, the large hollow voids of thestructural matrix are created by a series of circular opening thatextend throughout the material on all three plains and areinterconnecting and have opening spaces on all internal and externalsurfaces. The function of the hollow structural matrix 270 is identicalto the perimeter catch basin 230 created by the spacing between thechamber walls 110 and the internal permeable walls/partitions 250.

The structural matrix has an internal void space of at least 10% and avoid area of at least 25% on its surface making contact with the mediafiltration bed. Generally, the internal and surface void area of thestructural matrix is above 90% and therefore acts and functions justlike a 100% void space. Because the structural matrix has a largesurface void area it is commonly covered in a netting, screen or fabricwhich have openings smaller than the size of the granular media withinthe media filtration bed. The structural matrix is designed to be strongenough to hold the lateral loading of the media filtration bed.

Adjacent Storage and Filtration Systems

The horizontal flow wetland biofilter system is designed to be used as astand alone treatment system (FIG. 1, 2, 3, 4, 5) or in combination withupstream treatment or storage. In another embodiment, the chamber 100 isused in combination with an upstream storage system 600 which is placedbelow ground with a solid top (FIG. 7) and includes either an inflowpipe 290 from up stream collection systems and/or an grated opening 150built into the solid top to allow water to be directly conveyed into thestorage system 600. The storage system 600 can also have an open top(FIG. 8) which are commonly known as ponds, detention basins, or bioswales As water enters the storage system 600 the water level builds. Asthe water level builds it provides the head pressure needed to allow thewater to enter the chamber 100 through a connecting pipe 200. As thewater level builds in the storage system 600 it will build inside theperimeter catch basin 230 or hollow structural matrix 270 of the chamber100. As water builds it is forced through the media filtration bed 400and toward the center oriented vertically extending perforated tube 420.The tube 420 collects the treated water and conveys it downward andthrough the orifice plate 440 and out of the chamber 100 via the outflow pipe 300. The top of the chamber 100 has its catch basin covered byplates in configurations in which water is not wanted to enter directlyinto the perimeter catch basin 230.

Pretreatment Chamber

The chamber of the aforementioned embodiments can also be placedadjacent to a pre-treatment chamber that houses other treatmentprocesses to remove specific pollutants before entering the treatmentchamber of the said invention. Before water enters the chamber of thesaid invention is enters a pre-treatment chamber which is housed in thesame structure, but separated by a common wall. The pre-treatmentchamber contains an open area to encourage settling of particulates. Thepre-treatment chamber also houses a screening basket under the grated,curb or pipe opening into the chamber to remove trash and debris. Thepre-treatment chamber also houses filtration media which are housedwithin cartridges or other containers and contain filter media aimed atremoving small particulates and hydrocarbons which are known to cause amajority of clogging issues in media bed filtration systems.

In other embodiments, the horizontal flow wetland biofilter system isdesigned as a two chamber system (FIG. 9) the treatment chamber 100 anda pretreatment chamber 610. The two chambers share a common wall and areinterconnected via pipe or opening 200. The purpose of the pre-treatmentchamber is to remove particulate pollutants prior to the water beingconveyed into the treatment chamber 100 of the system. The pretreatmentchamber can incorporate various filtration processes to removeparticulates such as sediments, trash, debris and hydrocarbons. In oneembodiment the pretreatment chamber is designed with a large settlingarea 620 with the inflow pipe 290 and the pipe or opening 200interconnecting the pretreatment chamber 610 and treatment chamber 100raised of the floor to allow for the accumulation of sediment and otherparticulates. Water can also enter the pretreatment chamber from the topvia a grated or curbed inlet 150. In this embodiment the horizontal flowwetland biofilter system is a complete multi-stage treatment device forcontaminated water that contains various concentrations of particulateand dissolved pollutants. To provide additional treatment stages thegrate or curb opening 150 located in the top of the pretreatment chamber(FIG. 10) is fitted with a screening basket 160 that can remove largesolids such as trash and debris. The screening basket preventsfloatables from accumulating in the settling area 620.

In further embodiments, the pretreatment chamber (FIG. 11) 610 is fittedwith square, rectangular or round filter cartridges 170 that containfilter media with a central tube that is perforated to collect water andconvey it through a false floor 650 and convey the water into ahorizontal lying under drain pipe 660 which is connected to a pipe oropening 200 that transfers water into the perimeter catch basin 230 orhollow structural matrix 270 of the treatment chamber 100.

In other embodiments (FIG. 12), the pretreatment chamber 610 is filledwith filtration media 720 a majority of the height of the chamber. Underthe filtration media is an under drain material 710 made of a granularsubstance that are larger in size than the granules of the filter media720. Underneath the under drain material laying horizontally on thebottom of the pretreatment chamber 610 is a perforated tube the collectstreated water and conveys it through an pipe or opening in the chamberwall 200 and into the perimeter catch basin 230 of the treatment chamber100. The pretreatment chamber 610 in some embodiments (FIG. 13), has anopen top in which water can enter the chamber directly from the surfaceand flows downward through the filter media 720. In this embodiment, thefilter media 720 is exposed and incorporates living vegetation.

The design of the horizontal flow wetland biofilter system chamber 100is modular. Its design allows it to modular of various sizes. In someembodiments (FIG. 14), multiple chambers 100 can be placed side by sideas individual structures or share the same structure with a common andadjacent wall separating them. This configuration allows the system tobe used to treat a wide variety of pollutants with each chamber housingdifferent filtration media targeted at treating different pollutants.

Restriction Plate

Flow control through the chamber 100 is important in order to controlthe loading rate on the media surface and hydraulic retention timewithin the media filtration bed 400. Surface loading rate and hydraulicretention time are important variables that affect the performance ofthe media and its ability to remove pollutants. Specific retention timesare needed, specifically to allow for certain chemical reactions such asprecipitation and ion exchange to occur between the surfaces of themedia granules and dissolved pollutants. Most biofilter systems use thefilter media itself as the controlling factor or critical point ofrestriction for the flow through the system. The problem with thisconcept is as the media starts to clog the flow through the mediadecreases and the designed peak treatment flow rate is no longerreached. To overcome this downfall the horizontal flow wetland biofiltersystem (FIG. 15) is designed with an orifice, or restriction plate 440in the horizontally laying tube or pipe 300 which becomes the criticalpoint of flow restriction in the system. The maximum amount of flow thatcan go through the orifice at peak hydraulic head is less than thehydraulic conductivity of the media filtration bed 400. This allows thesystem to continue and operate at the same peak flow rate even as themedia may start to clog. This insures the system treats the specifiedamount of contaminated water over an extended period of time.

The size of the orifice is of specific size, hydraulically calculatedand tested to allow a set amount of water to process through theinvention when water within the chamber is at maximum level. Therestriction plate sets the peak treatment flow rate in the system. Theflow through the orifice is less than the flow rate through the mediafiltration bed itself. This provides a safety factor to account for anyclogging that may occur within the filter media itself over time. Othersystems peak treatment flow rate is controlled by the hydraulicconductivity of the media itself. With these systems as clogging of themedia starts to occur the flow rate through the media filtration beddecreases and therefore is no longer treating the amount of water it wasdesigned to treat.

Flotation Valve

In one exemplary embodiment, the flow control through the system isfurther enhanced (FIG. 16) by the inclusion of an internal floatationvalve 445 housed inside the tube. The tube controls at what level thewater must reach in the chamber before it is allowed to discharge out ofthe chamber. The reason for this device is to ensure even distributionof contaminated water throughout the vertical height of the mediafiltration bed's surface area over a range of different flow rates whichcorrelate to the wide variation of rain fall patterns. The flotationvalve 445 has three pieces: the float 470, the connecting rod 480 andthe valve stop 460. The bottom of the vertically extending perforatedriser 420 has a valve seat 450 in the bottom that prevents water fromflow through it and into the orifice plate 440 located in thehorizontally lying discharge tube 300 when the internal floatation valve445 is in the off position. The internal float valve remains closeduntil the water level in the treatment chamber 100 reaches a levelgreater than 50% the height of the chamber (FIG. 17). Once the waterreaches the specified height the internal float valve 445 raises withthe water level and the valve stop 460 raises above the valve seat 450and allows the water to pass downward around the valve stop 460 andthrough the valve seat 450 and then travels through the orifice plateand exit the chamber through the horizontal tube 300 and pass throughthe opening in the chamber wall 305. The internal float valve will onceagain close as water flow to the chamber 100 ceases and the water levelfalls below 50% the height of the chamber 100. To allow the water todrain all the way to the bottom of the chamber after the internal floatvalve 445 closes and the valve stop 460 sets inside the valve seat 450,a small flow orifice 490 is located on the bottom of the valve stop 460and spans the length of the valve stop 460 (FIGS. 18A, 18B). FIG. 18Aillustrates a front view of the small flow orifice 490 showing theopening, while FIG. 18B illustrates a side view showing the flow ofinfluent from a rear opening to a front opening of the small floworifice 490. A very small amount of flow is allowed through this smallflow orifice 490 which is substantially smaller than the flow controlorifice 440, and it therefore allows the chamber 100 to drain dry duringperiods when no water is being treated. Typically the flow rate thoughthe small flow orifice is less than one tenth the peak treatment flowrate of the treatment chamber.

Catch Basin Features

The configuration of the filtration chamber with a perimeter catch basinthat extends vertically between the media filtration bed and the wallsserves two distinct and unique advantages over traditional downward flowmedia filtration beds. First, it maximizes the initial media surfacearea for a given volume of liquid and thereby lowers the hydraulicloading rate on the media. The increased surface area improvesperformance and longevity of the biofilter apparatus and also providesan area for larger particulates that are contained in the influentcontaminated water to settle out before the water penetrates thefiltration media. Secondly, the horizontal flow prevents the largerparticulates from accumulating on top of a media filtration bed, as witha downward flow system where influent water is received on a top portionof the apparatus. The system is especially apt for treating contaminatedwater from parking lots, roads, rooftops and other areas whichcontaminated stormwater can originate.

Media Filtration

The media filtration bed contains granular filtration media such as butnot limited to: zeolite, expanded aggregate, perlite, activatedcharcoal, activated alumina, iron oxide, polymers, waste water residualsand other physical, biological, or chemical filter media. The mediafiltration bed incorporates a layer of non-organic soil-less growingmedia near the top of the media filtration bed column to assist in theestablishment of vegetation and to promote growth and longevity ofvegetative life. It does so by retaining moisture close to the surfacefor roots to tap into and establish themselves. The non-organicsoil-less growing media, such as stonewool or rockwool holds substantialmoisture and provides an ideal air to water ratio which is ideal forplant growth.

Horizontal Flow

Other flow paths such as horizontal or upward vertical flow have provento have fewer issues with clogging. Vertical upward flow has the leastamount of clogging issues but also has the most issues with channeling.The horizontal flow path provides minimized clogging and channelingconcerns and promotes good performance and longevity in biofiltersystems. Systems with horizontal flow media bed filtration also have theadvantage of being able to accept incoming stormwater subsurface viapipe or upstream storage system while still being able to growvegetation on the upper surface. Traditional downward flow systems havelimitations in this area along with having a large head drop betweeninflow and outflow points. In contrast, horizontal flow systems do notneed a large head drop between inflow and outflow points, as thehydraulic force of the water itself drives it through the filtrationmedia.

The horizontal flow path also allows the biofilter apparatus to beeasily connected to an adjacent pretreatment chamber which may houseother forms of treatment such as screening, separation and mediafiltration. These other forms of treatment can be easily incorporatedwith out additional head drop to further reduce the risk of clogging tothe media filtration bed.

Additionally, horizontal flow into and through media clogs slower whencompared to downward flow media bed filtration systems. Horizontal flowpath media filtration beds have the initial media surface extendingvertically so that the contaminated water makes contact first with themedia surface. Therefore, the media surface is parallel to the force ofgravity, which causes particles that make contact with the surface ofthe media to fall off and travel downward away from the surface of themedia.

Implementation

In general, the invention is used for the treatment of stormwater andsimilar contaminated water sources. This system is designed to beutilized in urbanized or other developed areas in which the percentageof impervious areas is generally high. The invention when utilized bythose skilled in the art is generally placed adjacent to any imperviousarea which generates rain water runoff or runoff of other contaminatedwaters from its surface. The invention also can be directly connected tospecific point sources of contaminated waters. When used in stormwaterapplications the systems is generally used to treat rain water andrunoff generated by human activities such a irrigation, car washing, andsimilar which are generated from parking lots, road ways, public plazas,industrial facilities, freeways and rooftops. Since the system has anopen top and that contains live vegetation, the system is generallylocated adjacent to hardscape or impervious areas when some form oflandscaping exists. The invention is generally located above ground withthe top of the chamber equal to the finish surface. In some embodimentsthe invention is located above ground to accept waters from rooftops orelevated plazas or bridges.

The modular design of the treatment chamber makes it easily scalable tovarious sizes and shapes, though generally square or rectangular. Theconcept of this invention also will work in a round orientation. Thehorizontal flow path through the media which makes it unique tobiofiltration systems in this field offers several advantages. Asmentioned the flow orientation of this invention minimizes cloggingconcerns when compared to downward flow systems. The invention alsocreates up to four times the media surface area for a given volume of amedia filtration bed. In one embodiment illustrated in FIG. 19, theinterior walls/partitions 250 of the media filtration bed 400 may havean irregular shape with a series of grooves 255 along its sides, furtherincreasing the surface area which interacts with the incoming influent.The horizontal flow path of the invention also offers allows for severalindividual chambers to be placed side by side in series without anyhydraulic drop in the chamber. By doing so several chambers can beplaced is series, with each successive chamber containing a filter mediathat offers higher levels of treatment. One example of this would be forthe first chamber to contain perlite to remove particulates, the nextchamber housing polymers to remove hydrocarbons, and the followingchamber housing activated alumina to remove dissolved nutrients.

The invention also can be placed adjacent to an upstream storage system.The advantage of this invention is no hydraulic head drop is requiredbetween the bottom of the storage system and the bottom on the saidinventions floor. With stormwater requirements moving toward volume basedesign a biofilter system which is easy to adapt downstream to a storagesystem is of need.

The above description of disclosed embodiments is provided to enable anyperson skilled in the art to make or use the invention. Variousmodifications to the embodiments will be readily apparent to thoseskilled in the art, the generic principals defined herein can be appliedto other embodiments without departing from spirit or scope of theinvention. Thus, the invention is not intended to be limited to theembodiments shown herein but is to be accorded the widest scopeconsistent with the principals and novel features disclosed herein.

1. A wetland biofilter chamber comprising: one or more outer side wallsand a floor section defining a substantially enclosed chamber with thetop open to the air; a media filtration bed disposed within the chamberand defined by one or more permeable inner side walls, wherein thepermeable inner side walls of the media filtration bed are separatedfrom the outer side walls of the chamber and define a catch basin forreceiving an influent; a collection tube disposed within the mediafiltration bed and extending vertically from a top portion of the mediafiltration bed to a lower portion of the media filtration bed; and atleast one outlet opening connecting the lower portion of the collectiontube with an outside of the chamber.
 2. The wetland biofilter chamber ofclaim 1, wherein the outer side walls and floor section are impermeable.3. The wetland biofilter chamber of claim 1, wherein the one or moreouter side walls include an intake opening to receive an influent intothe catch basin.
 4. The wetland biofilter chamber of claim 3, whereinthe intake opening is located on a lower half of a side wall.
 5. Thewetland biofilter chamber of claim 1, further comprising an outlet tubedisposed horizontally across the floor section of the chamber andconnecting the collection tube with the at least one outlet opening. 6.The wetland biofilter chamber of claim 1, wherein the collection tube ispermeable.
 7. The wetland biofilter chamber of claim 6, wherein thepermeable collection tube is perforated.
 8. The wetland biofilterchamber of claim 1, wherein the height of the collection tube isapproximately 5% to approximately 100% of the height of the mediafiltration bed.
 9. The wetland biofilter chamber of claim 1, wherein thecollection tube further comprises a restriction plate which restrictsthe flow of filtered influent to the outlet tube.
 10. The wetlandbiofilter chamber of claim 9, wherein the restriction plate is connectedwith a flotation valve disposed within the collection tube whichcontrols the restriction plate based on a level of influent in thecollection tube.
 11. The wetland biofilter chamber of claim 1, whereinthe catch basin has a width of approximately 0.1 inches to approximately10 feet.
 12. The wetland biofilter chamber of claim 1, wherein theheight of the inner side walls is approximately 25% to approximately100% of the height of the chamber walls.
 13. The wetland biofilterchamber of claim 1, wherein the thickness of the media filtration bed isapproximately 0.25 inches to approximately 80 feet.
 14. The wetlandbiofilter chamber of claim 1, wherein the catch basin includes asubstantially hollow structural matrix.
 15. A method of filteringinfluent in a biofilter chamber, comprising: receiving an influent intoa catch basin of the biofilter chamber with one or more outer side wallsand a floor section defining a substantially enclosed chamber with thetop open to the air, wherein the catch basin is disposed around an innerperiphery of the chamber between one or more outer side walls of thechamber and one or more inner permeable inner side walls of a mediafiltration bed; filtering the influent through the media filtration bed;collecting the filtered influent from the media filtration bed at acollection tube extending vertically within the media filtration bedfrom a top portion of the media filtration bed to a lower portion of themedia filtration bed; passing the filtered influent from the collectiontube to at least one outlet opening connected with an outside of thebiofilter chamber.
 16. The method of claim 15, further comprisingreceiving the influent into the catch basin from an intake openinglocated on a lower half of a side wall.
 17. The method of claim 15,further comprising receiving the influent into the catch basin from anopening in the top of the biofilter chamber.
 18. The method of claim 15,further comprising passing the filtered influent from the collectiontube to the at least one outlet opening using an outlet tube disposedhorizontally across the floor section of the chamber and connected on afirst end with the collection tube and on a second end with the at leastone outlet opening.
 19. The method of claim 15, further comprisingrestricting the flow of influent using a restriction plate disposedwithin the collection tube.
 20. The method of claim 19, furthercomprising restricting the flow of filtered influent when a flotationvalve disposed within the collection tube and connected with therestriction plate falls below a defined level.